Process of making friction facings



UNI E STATES PATENT oFFlc-i't.

FREDERICK C. STANLEY, OF \I BRIDGEPORT, CONNECTICUT, ASSIGNOR TO RAYBESTOS COMPANY, OF BRIDGEPORT, CONNECTICUT, A CORPORATION OF CONNECTICUT.

PROCESS OF MAKING FRICTION FACINGS;

1,417,778. NoDrawing.

T 0 all whom may concern:

Be it known that I, FREDERICK C. SrANLnY, a citizen of the United States, residing in the cityv of Bridgeport, county of F airfield,

and State of Connecticut, have invented certain new andfuseful Improvements in Processes of Making Friction Facings, of which the following is a specification.

This invention relates to improvements in process of making friction facings and re fers more "particularly to a clutch facing orbrake lining adapted for use in motor vehicles. I

The invention is directed to a novel process of making a friction facing from felted unwoven asbestos fibre saturated with a binder.

The object of'the invention is to provide a process by which the friction facing has a maximum tensile strength and hardness so that it can withstand the shocks to which these facings are subjected in a motor car and also will have sufiicient-resistance to abrasion; while at the same time it has the proper co-eflicient of friction. It is also necessary that the binder in these facings mustbe unaffected by oil or water in use, which object is accomplished by the present invention without in any way detracting from the other characteristics.

The process may be carriedfout as follows asbestos fibre preferably the 'short or low grade fibre is first ground in a suitable grinding machine or cutter. The ground material is then put into a beater mixed with the water or other solution and beaten into a pulp.

The pulp is then delivered to a paper making cent by the-weight of the asbestds fibre al-,

though this can be varied according to the characteristics of the product desired. This oxidizing agent facilitates or hastens the oureg of the binder and adds to the strength of the product and. also converts the binder into a form insoluble by oil or water. It also tends to produce a uniform curing throughout the mass during the curing operation herein- Specification of Letters Patent. Pat t M 30, 1922, Application filed September 24, 1919. Serial No.- 325,911. I

after described. It is to be noted that this reagent is put into the pulp before the formatlon of the sheet and not during the satu- *rating and curing steps of the process.

sufficient temperature to remove the water.

The sheet is then calendered to the desired thicknessand the frictionfacings are then out out of the sheet. The sheets are subjected to suflicient pressure in the calender to obtain as much tensile strength in the dry sheet as is feasible. The friction facings whether clutch rings or brake linings are now ready for saturation. The saturating tank is filled'with a binder. This binder may consist'of 94: per cent of linseed oil, 6 per cent of gilsonite in solution inthe oil the mixture being thinned with gasoline to about 33 Baum gravity. The frlction facings are then immersed while suspended on suitable rods in this binder solution for a period of half an hour. The friction facings are then removed and put in a closed steam oven and maintained at a temperature of about 200 F todrive off the gasoline which gasoline may be recovered and saved. This steam treatment is pr eferably continued from two The friction facings arel to three hours. y then removed to a closed baking oven where they are subjected to a temperature of about 250 F., for a period of twelve hours. The facings are then taken out of the oven and immersed in another saturating tank containing'a solution of 66 per cent of linseed oil and 33 per cent of gasoline, the gravity of the solution being about 33 Baum. This second immersion takes place for fromtwo to three minutes. In both of' the saturating steps double boiled linseed oil is preferable. The friction facings are then put into a second closed baking oven and maintained at a temperature of 300 F. for twenty-four hours. The heat in both of the baking ovens is preferably dry heat. The friction facings are then removed from the second oven and sand papered to micrometer s1ze and to get a smooth finish to the facing. The facings are now ready for use;

.I have given above'lan illustration in which theprocess is actually carried out in commercial operation. It is to be understood that the temperature and length of treatment are subject to reasonable variations dependin on the flexibility and strength require in the finished product. Also oils other than linseed oil' may perhaps in certain cases be used and other asphalts substituted for gilsonite. 1

During the baking operation, the, linseed oil, due to the presence of the air in the,

oven and also to the oxidizing agent in the sheet, is oxidized to produce a tough hard binder. The solubility of the linseed oil in gasoline before the baking treatments is clearly understood, I submit the following,

giving actual tests made on such friction facings I Average ten- Thickness of Thickness of sile strength ig g sheet before sheet after oi finished fi i h g calenderin calendaring facing in g in nches. in inches. poisipdisnper fi test The strength and hardness of the product made'by thisprocess is far in exess, in fact 1 from 1000 to 2000 lbs, upwards in tensile strength, over that heretofore obtained from any unwoven saturated friction facing and is even stronger than a woven sheet. The hardness also is proportionately increased over the friction facings heretofore made. It is to beinoted that in the baking operation,there,action develops autogenous heat or, in other words exo-thermic and care must be taken to prevent the material from becoming so highly heated'as to catch fire. This exo-thermic reaction results in the fact that the oxidation is of such a character as to generate heat a in addition to that externally applied. This exo-thermic reaction of oxidation is well known in other arts I .as for example'in the manufacture of air blown asphalt from petroleum residuum. Iclaim as my invention 1. A process of making a consisting in mixing asbestos pulp with an i oxidizing agent, forming the pulp into felt- V edrunw oyen sheets, dry ng and calendering.

the sheets, cutting out the friction facings, impregnating the facing with a binder con- 'manner may be more friction facing,

the facing, subjecting the facing to a second saturation'in a similar drying oil and subjectinig the facing to'a second baking.

. 2. process of making a friction facing, consisting in mixing asbestos pulp with an oxidizing agent, forming the pulp into felted unwoven sheets, drying and calendering taining a drying oil, and a. bitumen, baking V the sheets, cutting out the friction facings,

with a binder con-.-

impregnating the facing1 Ht b I v a 1 women, axing taining a drying oil an the facing at a temperature of 250 F. more or less, subjectin the facing to a second saturation in a rying oil and, subjecting the facing to a second baking at a temperture of 300 F. more or less.

3. A process of making a friction facing, consisting in forming a felted unwoven sheet, the major portion of which consists of asbestos fibre, forming friction facings of the desired configuration from said sheet and subjecting them .to a plurality of independent saturations and subjecting the facings to a separate baking operation after each saturation.

4. A process of making a friction facing, consisting in forming an unwoven sheet, the major portion of which consists of asbestos fibre, cutting friction facings out of said sheet, subjecting the facings to a plurality of saturations, and baking the friction facin after each saturation at 'a temperature su ficiently high to oxidize the drying oil and produce a maximum te sile strength in the facing and subjecting t a drying oil to th action of an oxidizing agent.

5. A process of making a friction facing,

consisting informing an unwoven sheet, the

major portion of which consists of asbestos fibre,1forming the friction facings from said sheet, subjecting the facings to a plurality'of saturations in a binder containing a drying oil, in separately baking the friction facing after each saturation at a temperature su'flicient to oxidize the drying oil and produce a maximum tensile strength of not less than 3000 lbs, to the uare inch.

6. A process 0 making friction facings, consisting in forming a facing of desired size and configuration, subjecting the facing to a lurality of saturations, in sub'ecting the riction facing to a separate aking treatment after each saturation, and contimiing the baking until the binder has bee1 in a mlneral oil' come substantially insolub such as gasoline.

' 7. A process of making friction facing' sp consisting in forming a facing of desired size and configuration, subjecting .the fac-' ing to a plurality of saturations in a drying oil, baking the facing after each saturation and continuing the baking. until the binder, has-become substantially insoluble in a mineral oil.

,- 8. A process of making a friction facing consisting in forming a facing, the friction surface of which consists essentially of asbestos fibre, saturating the facing with a waterproof binder and then baking the saturated facing in the presence of an oxidizing agent contained in the facing, the baking or curing operation being carried out under such a regulated temperature as to produce an exo-thermic reaction and oxidation of the binder.

9. A process of making a friction facing consisting in forming a facing, the friction surface of which consists essentially of asbestos fibre; saturating the facin with a waterproof binder and then be 'ng the saturated facing in the presence of an oxidizing agent contained in the facing, the baking or curing operation being carried out under such a regulated temperature as to produce an exo-thermic. reaction and oxidation of the binder.

10. A process of making a friction facing consisting in forming a facing having a substantially incombustible wearing surface and subjecting it to saturation in an oxidizable binder and then baking it in the presence of an oxidizing'agent contained in the body of the facing.

11. The process of making a friction facing, consisting in form' an unwoven felted friction facing containing at the time of the felting operation an. oxidizing agent of a nongaseous form, saturating the facing with a h drocarbon binder, and'in-then subjecting the facing to heat at an elevated temperature.

,12. The process of making a friction facing consisting of unwoven fibrous material, comprising incorporating with the'unwoven material an oxidizing agent, in forming the unwoven material with the oxidizing agent into a sheet, in saturating thesheet with an oxidizable binder, the saturated sheet.

13. The process of making a friction facing composed of unwoven fibrous material having an oxidizing agent 'incorporated therein, com rising saturating the facing with an oxidizable binder, and in then subjecting the facing to a heat treatand in then heating ment. a.

14. The process of making a friction facin conslsting in forming an-unwoven felte friction facing, containing an oxidizing agentin'a nongaseous form, 1n saturating t e facing with an oxidizable binder,

and in then subjecting the fa'cing to a heat treatment. g I v 15. The process of making clutch facings consisting in forming. an unwoven felted facing blank having a substantially incombustible wearing surface, subjecting the blank to saturation in an oxidizable binder, and in then subjecting it to heat at an elevated temperature, and at a step durin the processbefore treating the blank with the oxidizable binder incorporating into the material an oxidizing form.

16. The process of making a friction facing composed of asbestos fiber, which consists in subjectin the facing to inde-. pendent saturations -1n binders containing different relative quantities-of binder constituents forming the binder, and in subagent of nongaseous jecting the facing to a heat-treatment after each saturation. r

17. The process of making friction facings consisting of asbestos pulp formed 1nto unwoven sheets, in cutting friction facings from the sheet, impregnating the fac- I ings with a binder containing a drying oil, and bitumen, in then subjecting the facing to the presence of heat, in again saturating the facing with a drying oil and bitumen in relative quantities different from the qualitities composing the first mentioned bath, and in then again drying the facing.

' 18. The process of making friction facings comprising grinding vasbestos fiber into. a pulp, in saturating the pulp with water and a 'non seous; oxidizing agent, in form the pul into sheets,in cutting facings from the, sheets, in immersing the facings in a bath of oxidizable binding'material, and in then subjecting the facings to a heat treat-- containing iiferent relative uantities of binder constituents forming t e binder, each bath containing. an-oil and in heat the faoin after each batli. g

comprises subjecting the facing to inde- FREDERICK o. STANLEY. 

